Many conventional vehicles with internal combustion engines have some sort of heat recovery system. Heat recovery systems are used to recycle the thermal energy dissipated by the engine. Existing exhaust heat recovery systems can use a bypass valve between a bypass exhaust line and heat-exchanging exhaust line to control the flow of exhaust over the heat exchanger. This bypass valve must be actuated, either passively using a thermally active material or actively using either a vacuum or electric motor. One exemplary bypass valve is disclosed as an “exhaust gas flow diverging device” in U.S. Pat. No. 6,370,871 titled “Internal Combustion Engine Having Lean NOx Catalyst” to Suzuki et al. This device is, however, more complex than an inanimate flow regulator because it relies on electromechanical controls and is more prone to failure as it contains animate parts configured to perform within predetermined parameters.
It is taught in U.S. Pat. No. 7,628,144 titled “Supercharged internal combustion engine system” to Vetrovec to use a variable area nozzle to regulate nozzle mass flow rate in a supercharger application. This, however, is not disclosed and taught with respect to a vehicle exhaust heat recovery system with bypass.
Therefore, it is desirable to have a less complex and more reliable flow regulator for a vehicle exhaust heat recovery system with bypass.